That little poem has helped send children to bed for generations, and despite the ominous warning embedded in the rhyme, we scarcely take note of it anymore. But recent research seems to indicate we might need to consider adding a phrase about dirty laundry if we really want to make our kids feel safe from bedbugs.

Bedbugs are an ancient companion to mankind, and wherever people have settled, they’ve taken these little bloodsuckers with them. Bedbugs are tiny, reddish-brown insects that quietly feed on the blood of humans and animals while they sleep. Stories about bedbug infestations can be found throughout history. From a survival standpoint, they’re actually quite a success story. Unfortunately, it’s humans who’ve provided their meal ticket.

Although bedbugs were very much a part of the life of pre-20th-century Americans, from the 1930s until the 1980s you didn’t hear much about them in the U.S. and other developed countries. Opinions vary, but most experts attribute the decline to the widespread use of the insecticide DDT and other chemicals, as well as increased use of vacuum cleaners. In the 1990s, we began to hear about embarrassing outbreaks of bedbugs in swanky hotels and apartments; soon, bedbugs were on everybody’s mind again.

Bedbugs have been associated with unsanitary conditions, but the U.S. Centers for Disease Control and Prevention reports that’s largely a myth. “They’ve been found in five-star hotels and resorts and their presence is not determined by the cleanliness of the living conditions where they are found,” the CDC says on its website. Once established, the pests are notoriously hard to eradicate. The agency is quick to point out that bedbugs aren’t likely to carry diseases, but that’s cold comfort if you’ve been their midnight buffet.

How bedbugs spread and travel have been the subject of many scientific studies; common sense suggests they hitch a ride on our clothes, or crawl into suitcases. But recently, the University of Sheffield in England published a study that suggested bedbugs really love your dirty laundry. A pile of dirty clothes on the floor (say, in a hotel room) is apparently a powerful lure for bedbugs looking for a blood meal.

“There are a lot of good studies out there focused on trying to understand how bed bugs are attracted to humans and how they get around apartment blocks, but no one has really talked about how they get into the house in the first place,” study author Dr. William Hentley told the website Gizmodo. “Stopping people from bringing bed bugs home can be a big step in preventing them spreading throughout the world.”

In looking for a host, Hentley found, bedbugs are attracted to human odors. What better place to go hunting for a human being than a pile of sweaty clothes, full of smells from a day of sightseeing?

Hentley and his colleagues tested their theory by placing four tote bags of clothes — two full of clean clothes and two full of recently worn items — in two separate, temperature-controlled rooms. No humans were in either room, but carbon dioxide was released into the room to simulate human presence. The researchers found that bedbugs were twice as likely to be found on the dirty clothes as on the clean ones. The implication is a pile of worn clothes on the floor or in an open suitcase is like a flashing “welcome” sign.

“Our study suggests that keeping dirty laundry in a sealed bag, particularly when staying in a hotel, could reduce the chances of people taking bedbugs home with them, which may reduce the spread of infestations,” the study authors wrote.

So, the next time you travel, experts suggest putting your luggage up high on a metal rack, or even get some of those huge plastic zipper bags and place the entire suitcase inside. And if you’re really worried about this, visit the Environmental Protection Agency’s guide on how to do a really thorough search to make sure you can really sleep tight.